This invention relates to improvements in a circuit that is variously labeled a current pump, a controlled current source, or, when the input is a voltage, a bipolar voltage-to-current converter. As these names imply, the purpose of the circuit is to translate variations in an input signal of voltage or current into corresponding variations in current having a desired amplitude. This function can be performed by an open-ended circuit, but as is well known to those skilled in the art, variations in load, as well as in the characteristics of the active devices employed, can cause the variation in output current to differ substantially from the variation in the input signal. Considerable improvement has been attained by the utilization of feedback, generally positive but sometimes negative, to reduce the effects of variations in the characteristics of the ambient devices, but, depending on the particular circuit configuration employed, one or more of the following defects are present: general instability; instability when the load impedance is not significantly lower than impedances in the circuit; poor capacity for driving complex or active loads; potential for ground loop problems and difficulty in establishing a common reference because of the necessity for floating the load or the programming signal source; a small output voltage compliance in comparison with that normally available from the driving amplifier; the necessity for the programming signal source to supply load current; and a necessity for choosing between a high degree of current regulation at the risk of latch-up or a lower degree of current regulation with improved stability.